Since the Smithsonian's National Museum of Natural History began to collect marine specimens in the middle of the 19th century, the set has grown extraordinarily. The National Collection of Fishes now holds about 3.5 million fish.

The Smithsonian's curators have gathered digital X-rays of their collection in the book Ichthyo: The Architecture of Fish, which also features essays by oceanographer Jean-Michel Cousteau, ichthyologist Daniel Pauly, Museum of Photographic Arts director Deborah Klochko, and photo researcher Stephanie Comer.

This image shows a hookjaw moray eel, also called Bayer's moray, which skulks around reefs in the waters of Southeast Asia and Oceania.